The Exceptionally Luminous Type Ia Supernova 2007if

TL;DR

SN 2007if is an exceptionally luminous Type Ia supernova likely originating from a super-Chandrasekhar mass white dwarf, with observations indicating an unusually high brightness and potential circumstellar interaction.

Contribution

This paper presents detailed photometric and spectroscopic observations of SN 2007if, highlighting its extraordinary luminosity and exploring possible progenitor scenarios beyond the Chandrasekhar limit.

Findings

Supernova reached an absolute magnitude of -20.4

Requires ~1.5 solar masses of radioactive nickel

Possible progenitor is a super-Chandrasekhar mass white dwarf

Abstract

SN 2007if was the third over-luminous SN Ia detected after 2003fg and 2006gz. We present the photometric and spectroscopic observations of the supernova and its host by ROTSE-III, HET and Keck. From the H_alpha line identified in the host spectra, we determine a redshift of 0.0736. At this distance, the supernova reached an absolute magnitude of -20.4, brighter than any other SNe Ia ever observed. If the source of luminosity is radioactive decay, a large amount of radioactive nickel (~1.5 solar masses) is required to power the peak luminosity, more than can be produced realistically in a Chandrasekhar mass progenitor. Low expansion velocity, similar to that of 2003fg, is also measured around the maximum light. The observations may suggest that SN 2007if was from a massive white dwarf progenitor, plausibly exploding with mass well beyond 1.4 solar masses. Alternatively, we investigate circumstellar interaction that may contribute to the excess luminosity.